Many modern diesel engines have an exhaust system that features an exhaust gas recirculation (“EGR”) system that routes a portion of engine exhaust gas into an air intake system, such that a mixture of fresh air and engine exhaust is supplied to a combustion chamber during engine operation. In order to reduce certain pollutants found in exhaust gas of an internal combustion engine, such as NOx and particulate matter, several approaches have been tried, including using an after-treatment chemical in conjunction with a catalytic converter, a system often referred to as a selective catalyst reduction system or an “SCR system.” An SCR system adds complexity to an engine, and requires a catalyst that must be periodically replenished, which increases operating costs. If the catalyst is not replenished, the engine exhaust typically will not meet emissions standards, and the engine may be required to cease operations.
Therefore, a need exists for an engine capable of meeting emissions standards without the use of an after-treatment system to control parameters useful in reducing emissions of the engine.